Mechanical stoker



Feb. 26, 1929.

, "M. WIGHTMAN MECHANICAL STOKER Filed May 10, 1924 8 Sheets-Sheet 1INVENTO 7 M 77f.

BY o ATTORNEY Feb. 26, 1929. 1,703,130

M. J. WIGHTMAN v MECHANICAL STOKER Filed May 10, 1 924 8 Sheets-Sheet 2%w ATTORNEY Feb. 26, 1929. 7 1,703,130

M. J. WIGHTMAN MECHANI CAL STOKER Filed May 10, 1924 8 Sheets-Sheet. 3

44 ATTORNEY Feb. 26, 1929. 1,703,130

M. J. WIGHTMAN MECHANICAL STOKER Filed May .10. .1924

8 Sheets-Sheet 4 C30 h l INVEN% 5 W Maw/5477 %w ATT-ORNEY M. J. WIGHTMANMECHANICAL swoxsn Filed May 10, 1924 Feb. 26, 1929.

Feb. 26, 1929., r

' M. J. WIGHTMAN MECHANICAL STOKER Filed May 10 1924 8 Sheets-Sheet 6INVENTQR ATTORNEY removing the ashes as the incoming Patented Feb. 26,1929.

UNITED STATES MERLE J. WIGHTMAN, or

5mm comrmy.

wEsu: NEW BRIGHTON, or NEW YORK, N. Y., A coaroaa'rron or DELAWARE.

NEW YORK, ASSIGNOR TO DOMESTIC MECHANICAL STOKER.

This invention relates generally to mechanical fuel stokers and moreparticularly to a combined stoking device and burner especially adaptedfor use. with solid fuel in furnaces of the dences or in otherrelatively small installations.

A general object of the invention is to provide an apparatus which willautomatically feed and burn the cheaper forms of coal with a minimumdegree of attention and in such manner as to provideasubstantiallycomplete or perfect combustion thereof and an efficientapplication and use of the heat thus obtained. A further object of theinvention is to provide means operated in conjunction with the stokingand burner mechanism for depositing them in a suitable receptacleoutside the furnace.

The invention includes an improved burner of the underfeed type havingmeans for intermixing the heated and incandescent coal at the uppermostpart of the fire bed with fuel mass beneath. 'In combination with the.burner a baflle member is provided above the burner for deflecting heatwaves against the outermost portions of the fuel layer to insure thecomplete combustion thereof and against the side walls of the fire potchamber, in order to distribute and make the most eflicient use of theheat obtained.

In a preferred form of the invention the improved burner includesmounted annular fire pot member having its inner surface formed to movethe directly engaged fuel particles downwardly into the fresh fuel toproduce a preliminary gasification and cokingof the main body ofincoming fuel. A group of rod-like members extends into the fuel massfrom the bafile member and prevents the mass as a whole from rotatingand thereby facilitates the intermixing action of the annular member.

The invention includes an intermittently operated burner feedingdevicehaving an adjustable and intermittent clutch connection with anelectric motoror other suitable source of power. The motor serves alsoto drive a fan or blower for forcing a draft of air into a jacketedspace enclosing the fire ot in order to cool the eat theair and supplyheated air to the burning upper portions of the fuel mass to assist inthe complete combustion thereof.

type used in heating res1-- they are formed and a rotatably operatingparts, pre- An ash-removing conveyor forms a part of the generalorganization of structure and is arranged to be driven by the motor at acontrolled spe'ed-corresponding to that of the fuel feeding device.

Another feature of the invention includes cooperating adjusting meansproviding for varying the speed of the feeding operation and at the sametime varying the volume of air delivered by the blower in a ratio to thefuel feeding operation which can be itself varied in secondaryadjustments to suit the draft requirements of different fuels. x.

Other features of the invention include a removable'grid for thecombustion zone of the fire pot; a removable unitary bearing structurein which a driving connection between the fuel feeding device and therotatable fire pot is ,journaled; means for removing accumulated dustfrom the air jacket space; and driving clutch mechanism for the feedingdevice which provides for manual oscillation of the feed mechanism atwill for the purpose of 'dislodging obstructions.

Still other features of the invention will be hereinafter referred to.

In the drawings,

Figure 1 is a view in end elevation (with an unimportant part brokenaway) of a fuel handling apparatus embodying the invention.

Figure 2 is a view in side elevation on a reduced scale of the apparatusshown in Figure 1.

Figure 3 is a plan view of the apparatus shown in Figure 2 taken on theline 3-3.

Figure 4 is a view in vertical section of a burner construction formingpart of the invention.

. Figure 5 is a view in horizontal section of 95 the lower part of theburner, showing a cleanout device.

Figure 6 is a sectional view showing a portion of the burner and asupport for the framework therein. 100

Figure 7 is 'a sectional view of the reducing gear takenson the line 77of Figure 1.

Figure 8 is a vertical section on an enlarged scale taken approximatelyon the line 8-8 of Figure 1.

Figure 8 is a sectional view taken on the line 8"-8 of Figure 8.

Figure 9 is a horizontal section of the device shown in Figure 8.

Figure 10 is a front elevation on an en- 110 larged scale of clutchdriving device shown in Figure 1.

Figure 11 is a view in section showing ash removing mechanism formingpart of the invention and taken on the line 1111 in Figure 1.

Figure 12 is a view in cross-section showing a detail and taken on theline 12-12 of Figure 11.

Figure 13. is a cross-section taken on the line 13-13 of Figure 11.

Figure 14 is a view similar to Figure 4 showing a modified form ofburner mechamsm. p

Figure 15 is a plan view, partly in section, of the device shown inFigure 14.

Figure 16 is a sectional view on an enlarged scale showing a detail ofthe clutch mechanism.

Referring to the drawings for a more detailed description of theinvention, the general organization of structure includes a burner 20connected through the concentrically disposed tubular members 21 and 22with a fuel hopper 23 and the outlet pipe 24 of an air blower 25. Theinner tubular member-21 is fitted with a screw conveyor 26 for feedingfuel from the hopper 23 into the base portion of the burner or fire pot20. In order to operate the fuel feedin device and the blower anelectric motor 27 is directly coupled to the blower 25 and is indirectlyconnected to the shaft of the fuel feeding conveyor 26 through areducing gear set 28 and an intermittently acting clutch device 29.

Another element of the general organization of structure resides in anash-removing device which includes a screw conveyor 30 mounted beneaththe draft conduit 22 and extending into the base of the furnace beneaththe fire pot 20 as is shown in Figure 2 of the drawings. At a pointbeneath the hopper 23 the ash conveyor turns off at right angles andinclines upwardly to deliver ashes into a suitable receptacle 31 asindicated in Figure 1. A sprocket-wheel 32 on the end of the ashconveyor shaft is connected through a sprocket chain 33 with a drivingsprocket-wheel 34 on the shaft of the fuel conveyor 26 so that the ashconveyor is driven in exact accordance with the operation of the fuelfeed conveyor.

Taking up the various elements of the general structure-the burner orfire pot structure 20 will be first described. Referring to Figure 4 ofthe drawing the fire pot structure proper includes a stationary basemember 35 having a horizontal passageway 36 in which the delivery end ofthe conveyor 26 is received, and an upwardly directed outlet 37 throughwhich the fuelis .forced by the actionof the conveyor into a chamberformed by a rotatable annular body member 38. The annular member 38 ismounted for rotation on ball bearings 39- rolling in a raceway formed inthe annular track member 40 and gear teeth 41 which mesh with a drivingspur gear 42. The spur gear 42 is provided with a bevel spur gear 43which meshes in turn with a bevel spur gear 44 carried on the squaredend 45 of the shaft 46 of the con-' veybr 26. It will be seen that theconveyor shaft 46 passes through and is journaled in the wall of thebasemember 35 opposite the passageway 36. The combined spur gear 42 andbeveled spur gear 43 are mounted on a shaft 47 journaled in a support 48which is directly attached to a base or floor member 49 and provides aunitary driving connection between the conveyor shaft and the annularmember 38 which can be readily removed for inspection or repair whendesired.

An important feature of the invention resides in the particularconstruction of the annular body member 38 of the general fire potstructure. It will be seen that the inner surface of the annular member38 is provided with a series of helically formed cam members 50, "whichin the rotation of the annular member in a counter-clockwise direction,operate to depress and intermix engaged heated particles of the mass offuel contained within the annular member with the mass of incoming freshand cool fuel enter7ing from the conveyor discharge outlet 3 In order toprevent the rotation of the mass of fuel as a whole and to therebyfacilitate the depressing and intermixing action of the rotating cammembers 50, a group of rodlike members 51 are so supported as to projectinto the mass of fuel and by reason of their fixed position preventrotation thereof. The rod members 51 may be conveniently supported by abaflle plate 52 having a removable central portion 53-from which therods 51 depend as is clearly shown in Figure 4 of the drawing. Forconvenience in removing the rods 51 from their position for any purpose,the supporting plate 53 may be removed from its position in the baflleplate through the use of a hook member 54 attached thereto.

It will be seen that the mass of fuel is gradually fed upwardly throughthe main body portion of the fire pot member to a combustion zone at theuppermost part thereof and in order to facilitate the combustion of thefuel in the most effective manner a grid member 55 is provided whichtakes the form of an annular perforated and slotted rim with respect tothe annular member 38. The slots which are radially disposed, as shownin Figure 15, perinit the rim to expand andeontract readily in responseto temperature changes. The grid member 55 is removably engaged with aframe member 56 of the fire 1 pot structure and is provided withinwardly PIOJBCtlIig pin members 57 which upon the is provided with anintegrally formed set of surface of rotation of the id member can bemoved into or out of we ging engagement with conical lower surfacesformed on the heads of retaining screws 58 carried by the frame member56. It will be seen that with this arrangement of structure theincandescent fuel is gradually Worked outwardly over the upper the grid55 until it has been entirely consumed and the residue has fallen overthe outer edge of the grid into the space surrounding and beneath thefire pot structure.

The combustion of the fuelresting on the grid member is furtherfacilitated by the action of the bafile plate 52. The position of thebaffle member 52 is such as to reflect heat waves inwardly and outwardlyacross the fuel resting on the grid to thereby insure the completecombustion of the fuel in its movement outwardly across the grid andalso to reflect heat waves outwardly between the bafile and grid membersagainst the inner surface of the furnace chamber. The battle member maybe conveniently supported on the gridmember through the use of spacingsleeves 59 and bolts 60.

In order to produce a suitable draft of air through the burning fuel tofacilitate the combustion of the fuel, the fire pot structure isenclosed in ajacket or casing 60' which is spaced therefrom to providean air chamber or reservoir 61 into which air under pressure is forcedthrough the conduit member 22 already referred to. A portion of the airdelivered from the conduit 22 enters the lower portion of the mass offuel contained in the annular member 38 through a narrow slit or opening62 between the lower extremity of the annular member 38 and the basemember 35 of the fire pot structure. The greater portion, however, ofthe air entering the jacket. 60 from the conduit 22 passes into thechamber 61 where it is heated by contact with the hot body member 38 ofthe fire pot and then passes through ports 63 in the frame member 56 andthrough the annular opening 64 be tween the frame member 56 and theannular member 38 into a space 65 beneath the perforated grid member 55.The air arriving in the space 65 is still further heated and then passesthrough the annular slit or 'opening 66 between the upper extremity ofthe annular member 38 and the grid member 55 and also through a seriesof ports or passages 67 formed in the grid member 55 into the mass ofincandescent fuel resting on the upper surface of the grid member. Itwill be seen that with this'structural arrangement air is supplied tothe main body ofv fuel contained in i the annular member 38 and a stillgreater supply of air is supplied, after being preheated, to theincandescent fuel in the combustion zone adjacent to the rim or gridmember 55. With the forced draft which is thus provided a thoroughcombustion of inferior grades 0 fuel can be produced so that the burneras a whole operates with a high degree of efliclency.

In order to clean out the jacket chamber surrounding the operating partsof the fire pot if an accumulation of dust may have been producedtherein, clean-out openings 70 are provided in the floor plate 49 of thedevice and are normally covered by a shutter or cover plate 71 which isrotatably mounted on an annular stud 72 on the upper surface of thefloor plate 49 and can be rotated into or out of closing relation to theopenings 7 0 by means of a rod 73 operable from ahandle member 74 andnormally moved into closed position by the action of a spring 75. ItWill be seen that when the cover plate 71 is moved to open position thata draft of air entering from the air conduit 22 will blow anyaccumulation of dust that may have gathered in the jacket chamberoutwardly through the openings 70.

The mechanism employed for feeding fuel from the hopper 25 into theburner 20 is arranged to intermittently rotate the screw con veyor 26through a predetermined fractional part of a revolution with eachoperating movement. Referring to Figures 8 and 9 of the drawings it willbe seen that the conveyor shaft 46 passes through the reduced baseportion 76 of the hopper 25 and is journaled in a boss 77 formed on theforward face of the hopper base. The outer end of the conveyor shaft 46is provided with driving clutch mechanism indicated generally at 29 andillustrated particularly in Figures 1, 8, 9 and 10 of the drawing.

Referring to this clutch mechanism, sleeve 78,;which is providedwith theflange 79, is keyed to the conveyor operating shaft 46. This sleeve, asshown in'Figure 8', has a sector shaped gap 80 in which is located thedriving lug 81 which is secured to the drum 82. By means presently to bedescribed the drum 82 is given an oscillatory movement in which it movesa greater distance on its forward stroke than upon its return. Thedifference between its two strokes. which may be adjusted as will beexplained later, is what determines the extent to which the flange 78.and hence the conveyor operating shaft 46, will be advanced by thedriving lug 81 at each complete oscillation of the clutch mechanism.Obviously, if the forward and return strokes of the lug 81 were equal,that lug would mere- 1y oscillate back and forth in the sectorshaped gapof the flange 79 without advancing the flange or the conveyor shaft 46to which it is secured. v

The means for oscillating the drum 82 as above stated will now bedescribed. Surrounding t e drum 82 is the split band 83 upon the t endsof which are secured the brackets 84 and 85. To the bracket 84 ispivotedone end of the clutch operating arm 86 f which atitsother end ispivoted to the conthe vanced at all. However, when the abutment nee-tingrod 87 operated by the motor driven crank 88. The arm 86 is alsoconnected to the bracket 85 by means of the link 89. As a result of thisconstruction, as the arm 86 is moved forwardly or in a counter-clockwisedirection as viewed in Figure 10, it tightens the band 83 on the drum 82and carries the band and drum with it. So, also, the spring 90, which isinterposed between the bracket 84 and the end of the rod 91, exertssuflicient force tending to move the arm toward the bracket 84 that evenupon the return (clockwise) movement of the arm 86 the band 83 will gripthe drum 82 with suflicient friction to carry the drum back with it, ifthe return movement of the drum is unobstructed.

In order that there may be the required difference between the forwardand return strokes or movements of the drum 82 to effect the desiredadvance of the conveyor shaft, I provide means for obstructing thereturn -movement of the drum 82 at any desired point on the returnmovement, of the band 83 and arm 86. I These means comprise the twosegmental friction brake members 92, 93 located within the flange of thedrum 82. The lever or regulating arm 94 is pivoted to the brake member,92, and has a projecting pin 95 adapted to contact with the other brakemember 93. The spring 96 normally presses against the lever 94 in such away as to tend to separate the adjacent edges of the two brake membersand thus to expand them into frictional engagement with the innersurface of the flange of drum 82. A fixed abutment 97 and an adjustableabutment 98 are pro vided for. limiting the movement of the lever 94,which lever, as will now appear, operates to limit the rotary movementof the brake 92, 93 as a whole, as well as to control its frictionalengagement with the drum 82. I

Assume now that the parts are at the beginning of their forward stroke.The cushioned end 99 of lever 94 will then be in contact with the fixedabutment 97. The movement of the arm '86 in' its counter-clockwise(forward) direction will, for reasons previously stated, carry with itthe band 83 and drum 82, and also the brake members 92, 93 (which arepressed into frictional engagement with the drum 78 by the spring 96)and the brake controlling lever 94. If, now, the adjustable abutment 98were not so placed as to intercept the lever 94 in its forward movement,all of the parts above mentioned, including the drum 82 and its drivinglug 81, would oscillate back and forth together, the return stroke ofeach being equal to its forward stroke. The result would be, asbeforestated, that the conveyor shaft would not be ad- 98 is placed inan intermediate position, as shown, for example, in Figure 10, the end99 of lever 94 is arrested by its prior to'the completion of the forwardstroke of arm 86.

The result is that the brake also is arrested, its frictional engagementwith drum 82 being lessened by the, tendency of the lever 94 to move ina clockwise direction about its own pivot. The arm 186, band 83 and drum82, however, continue on to the completion of the forward stroke. At thecommencement of the return stroke the spring 96 againbecomes effectiveto bring the brake members into frictional engagement with the drum 82,and, the brake being now free to rotate sequent operations of the clutchmechanism the same cycle isrepeated. It is in this way that the returnstroke of the drum is rendered of less extent than its forward stroke.Thus the distance between the abutments 97 and 98 measures the extent ofthe return stroke of the drum. The closer these abutments are togetherthe less will be the return stroke of the drum and the greater thedifference between its forward and return stroke. And'as abovesuggested, the greater this difference the greater will be the advanceof the con- .veyor operating shaft upon each operation of the'clutchdevice. Thus the maximum rate of feed is obtained when the adjustableabutment 98 is in its uppermost position so that the lever 94 is notpermitted any movement, and the minimum rate is determined by thelocation of a second fixed abutment 100. The adjustable abutment 98 maybe placed anywhere between these two positions, depending upon the rateof feed desired. The position of the stop 98 may be fixed by aband screw101 which is utilized to lockctheband' 102 on which the stop 98 iscarried in fixed angular position. The band 101 is rotatably mountedonthe boss 77 as is clearly shown in Figure 8 of the drawings.

The adjustable stop member 98 may, if desired, be left unlocked and freeto be moved from a distance through a. chain or other connection with amanual or thermostatic control device located in another part of't'hebuilding in which the device is used.

The loose connection provided between the clutch drum 82 and theconveyor shaft through the gap 80 in the flange 79 afl'ords anadditional useful function and that isthe capability of manuallyoscillating the conveyor shaft through a partial revolution for thepurpose of dislod 'ng clinkers or for any other purpose." 3% facilitatethis a square recess 103 in the outer end of the conveyor tour of the cashaft 46 provides for the introduction of the furnace ash pit to thetransfer box 132. The uared end of a crank or wrench for rockpipe orcasing 120 is cut away as at 121 to ing the shaft. Should it be founddesirable permit ashes to enter the casing and be ento increase thelength of the normal operating gaged and removed by the conveyor. strokeof the arm 86 the link 87 maybe at- The function of the transfer box132' is to tached thereto at the position of the hole 109 transfer theashes from the action of the horiinstead of at the outer extremity ofthe arm. zontal conveyor 30 to the action of a non-hori- In order toregulate the volume of air supzontal conveyor such as the upwardlyinplied to the burner through the draft conduit clined conveyor 127located within the pas- 22 a butterfly or damper valve 112 is providedsage 133.. This latter conveyor carries the 76 in the air supply pipe 24and a shaft 113 for ashes from the transfer box 132 to the ash adjustingthe valve extends therefrom and is can 31- The provision of the g ide01' hafi journaled in a bracket lug 114 on the hopper 131 within thetransfer box facilitates the base member 76. change 'of direction whichthe ashes are Provision is: made for automatically adforced to takewithin the transfer box in passjusting the position of the valve 112 toacing, and the guard 133 (Figs. 11 and. 12) cord with the position ofthe feed control arm serves to shear ofi large clinker which may 98 andthe rate at which fuel is fed to th be carried into the transfer box bythe horiburner. For this purpose a crank device 115 zontal conveyor 30.

d by the shaft 113 and i It is, of course, important that means he isa-djustably carrie engaged by a screw 116 passing through an provided toprevent the accumulation and arm 117 fixed to the shaft. Rotation of thecrowding of large amounts of ashes within screw 116 is utilized to varythe angular rethe transfer box, since such accumulati n lation of thecrank 115 to the valve shaft 113. m gh cl g he machine. To this end I S0The automatic adjustment referred to is obpr p rti n the gears 129(which as will be tained by the cooperation of the crank 115 noted areprotected from contact with the with a cam member 118 carried by thering ashes) that the non-horizontal conveyor 127 or band 102 whichsupports the feed control rotates at a speed which is slightly morerapid stop 98. It will be seen that the cr nk arm than that of thehorizontal conveyor 30.

115 is caused to engage and follow the con- Amodified form of burner orfire pot struc- 06 m 118 through the action of a ture is shown inFigures 14 and 15. In this weight 119 conveniently forming the head ofmo ifi t on h main body P II 5 f the adjusting screw 116. Furtheradjustthe fire pot structure is fixed against rotation ment of therelation between the air valve 112 while the rods 136 are given arotative mo and the feed control mechanism to suit the n Wi h n h ma s ff Th o 136 1 requirements of different fuel may b obare carried on arotatable member 137 located tained by varying the angular position ofthe twe n he member 135 and the base memcam 118 on its support. This isachieved by her 35 of the'fire pot. In general this form loosening thescrew 118, adjusting the cam, of burner follows that shown in my prlorand then looking the cam in adjusted posi- ,Patent No. 1,454,697; May 8,1923.

tion by turning the screw to its holding posi- The general operation asa complete opertion. It will be seen that with the arrangeatin unit ofthe described apparatus may be ment of ad'usting mechanism shown anydebrie y summed up as follows: The hopper 25 sired relation between therate of feeding is filled with coal inarelatively finely:J1 ivided' fueland the rate of supply of air to the grade such, for example, as thesize own as burner may be obtained, and that the adjustbuckwheat. A firehaving been kindled in ment of the feed control arm 86 automatitheburner 20, current to the electric motor 27 ding adjustment is turned onand the blower 25 through its cally produces a correspon of the airvalve 112. Y direct-coupled connection with the motor is It will beobserved that the burner 20 and started into operation. At the same timethe a frame work 122 on which the motor 27 and crank 88 is set intorotation through the rotaother parts are mounted are raised above thetion of the worm wheel 104: in the reducing floor 123 on posts 124thereby placing the gear set 28 by the worm 105 directly driven artsincluding the burner at a convenient from the motor shaft 106 throughthe flexible level as well as providing room for the ash couplin 107,the crank 88 being mounted on removing device beneath the otherstructural the sha t-108 of the worm wheel 104. parts. It will be seenthat the framework 122 .The oscillation of the clutch operating arm andthe parts carried thereby are placed to through its operating connectionwith the one side of the hopper 23 and in a relatively crank 88 and theresulting intermittent operprotected location beneath the overhang ofation of the fuel conveyor 26 has already been 125 the correspondingside of the hopper. described. It will be clear that when once The ashremoving device which has been set into operation the fuel conveyorwill'congenerally referred to, includes the screw continue to feed fuelto the burner, subject only veyor 30 which is located within thehorizonto regulation of the rateof supply of fueland ta pipe or passage120 and extends from the air by variations in the position of thecontrol arm, until the supply of fuel in the hopper has been exhaustedor until the supply of power to the motor has been shut off.

The driving connection between the fuel conveyor and the rotatableburner structure produces the desirable intermixing of the hotincandescent fuel at the upper part of the fuel bed with the coolerincoming fuel below thus obtaining the desirable gasifying and cokingeffect which is an important feature of the invention.

The driving connection between the fuel conveyor shaft and the ashremoving device insures the automatic removal of ashes so that theapparatus operates with a minimum degree of attention, requiring onlythe replenishing of the hopper with a fresh supply of fuel every two orthree days and the substitution of an empty ash receptacle for a filledone at relatively infrequent intervals.

What is claimed is 1. In a heating plant for household use, a fire potprovided with a combustion zone in the uppermost part thereof, a screwconveyor for feeding fuel into the base portion of the fire pot .andupwardly therethrough into said combustion zone, a screw conveyormounted beneath the fuel feeding conveyor and extending substantiallyparallel thereto into aposition beneath said fire pot to remove ashesfalling therefrom, means for rotating the fuel feeding conveyor, and adriving connection between the outer end of the fuel feeding conveyorand the outer end of the ash removing conveyor.

2. In a heating plant, a fire pot supported above the base of a furnacechamber, a fuel hopper located outside the furnace, a tubular memberconnecting the hopper and the base of the fire pot, a screw conveyor insaid tubular member operable to feed fuel from the hopper into the firepot, a tubular member surrounding the fuel feeding member and spacedtherefrom to provide a conduit through which air may be forced into thefire pot, an ash conveyor located beneath the air conduit and extendinginto the furnace to remove ashes discharged from the fire pot, a blowerarranged to force airthrough the conduit, a motor having a directdriving connection with the blower, and -a speed reducing driveconnection between the motor and the fuel and ash conveyors.

3. In a burner construction for furnaces, a stationary base memberprovided with a fuel passageway having an upwardly directed dischargeoutlet, a rotatable annular body I member provided on its inner surfacewith fuel engaging members operating in the rotation of the annularmember to depress and intermix engaged heated fuel particles with freshfuel entering the annular member from beneath, an annular grate memberlocated at the upper edge of the rotatable body member, a bafile membersupported above the grate member and arranged to deflect heat wavesagainst fuel on the grate member and cross the edge of the grate intothe furnace chamber, and rod-like members depending from the bafilemember and arrangedto project into the fuel mass to prevent bodilyrotation thereof.

4. In a burner construction for furnaces, a stationary base memberprovided with a fuel passageway having a laterally directed inlet and anupwardly directed outlet port, a screw conveyor operating in said inletport with its shaft extending through and journaled in the wall of thebase member, a rotatable annular burner body member provided on itsinner surface with fuel engaging members operating in the rotation ofthe annular member to depress and intermix engaged heated fuel particleswith fresh incoming fuel, an annular removable grate member located atthe upper extremity of the annular body member and across which fuel isfed from the rotating body member, and means consisting of a removableunitary gear connection between the end of the conveyor shaft and therotatable annular member.

5. In a stoker for a burner of the underfeed type, a fuel hopper, a pipeextending between the hopper and the base of the burner, a screwconveyor operating in the pipe for feeding fuel from the hopper to theburner, a clutch device carried by the conveyor shaft, a motor having acrank connection with the clutch device for intermittently driving thefuel conveyor, an ash remover including a screw conveyor mounted beneathand substantially parallel to the fuel conveyor, and a sprocket andchain driving connection between the fuel conveyor and the ash remover.

6. In a stoker for a burner of the underfeed type, a fuel hopper, a pipeextending between the hopper and the base of the burner, a screwconveyor operating in the pipe for feeding fuel from the hopper to theburner, a clutch device carried by the conveyor shaft, a motor having acrank connection with the clutch device for intermittently drivin thefuel conveyor, an ash remover including a screw conveyor mounted beneathand substantially parallel to the fuel conveyor, a sprocket and chaindrivin conveyor an the ash remover, and an exconnection between the fueltension to the ash remover projecting sub-.- stantially at right anglesand atan upward inclination to t e ash remover roper,

7'. In a solid fuel burner oft e underfeed type, a fire pot, means forfeeding fuel into t e lower portion of the fire pot, means fordepressing heated fuel particles in the combustion zone at the upperportion of the fire pot into contact with cooler fuel particlesbeneath,and a bafile plate mounted above the fire pot to d fleet heatwaves outwardly across the upper extremity thereof.

1 8. In a fuel burner of the underfeed type, a fire pot, anannularremovable grate member adapted to be placedin the relation of anoutwardly and radially extending flange to the upper edge of the firepot, a support for the grate member, upstanding headed members on thesupport having the under side of the heads in the form of invertedcones, and radially extending pins'on the grate adapted to be forcedinto wedging engagement with the under side of the heads when the grateis partially rotated to thereby lock the grate in place.

9. In a solid fuel burner ,of the underfeed type, a horizontallypositioned screw fuel conveyor extending into the lower portion oftheburner, a fuel stirring device rotatable about a vertical axis, abevel pinion on the end of the conveyor shaft, said stirring devicebeing provided with gear teeth, and a unitary and removable gearconnection for said conveyor shaft and said stirring device comprising,a vertical counter shaft, an elongated bearing support forthe countershaft, and a combined bevel and spur gear member carried b bevel pin1onon the conveyor shaft and with the gear teeth on the stirring device.

10. In a heating plant, a fire pot supported above the base of a furnacechamber, a fuel hopper located outside the furnace, a tubular memberconnecting the hopper and the base of the fircpot, a screw conveyor insaid tubular member operable to feed fuel from the hopper into the firepot, an air chamber surrounding said fire pot, a tubular membersurrounding the fuel feeding member and spaced therefrom to provide aconduit through which air may be forced into the air chamber andtherefrom into the fire pot, an

ash conveyor located beneath the air conthe shaft and meshing with theduit and extending into the furnace to remove ashes dischar ed from thefire pot, a blower arranged to orce air through the conduit into saidair chamber, an opening in the bottom. of the air chamber normallyclosed by a shutter, actuating means connected to said shutter andadapted for manual operation whereby said shutter maybe moved to exposesaid opening to permit the air blast in said chamber to blow out anydust that may accumulate, a motor having a direct driving connectionwith the blower, and a speed reducing drive connection between the motorand the fuel and ash conveyors.

11. In-a heating plant, a fire pot supported above the base of a furnacechamber, a fuel hopper located outside the furnace, a tubular memberconnecting the hopper and the base of the fire pot, a screw conveyor insaid tubular member operable to feed fuel from the hopper into the firepot, a driving clutch device mounted on the conveyor shaft in such amanner as to permit oscillation of the conveyor shaft by handindependently of the clutch device, a tubular member surroundingthe'fuel feeding member and spaced therefrom to provide a conduitthrough which air may be forced into the fire pot, an ash conveyorlocated beneath the air conduit and extendin into the furnace to removeashes discharge from the fire pot, a blower arranged to force airthrough the conduit, a motor having a direct driving connection with theblower, and a speed reducing drive connection between the motor and thefuel and ash conveyors.

MERLE J. WIGHTMAN.

